BIOLOGY

Question 1

Assertion: Early wood is formed during spring season.
Reason: Cambium is very active in spring season and produces a large number of xylary elements having vessels with narrow cavities.

Answer 1

B) A is true but R is false.
In spring season the cambium is very active and forms xylary elements having vessels with WIDER cavities.

Question 2

A: In dicot stem the amount of secondary phloem is more than secondary xylem.
R: The cambium is generally more active on the inner side than on the outer.

Answer 2

C) A is false but R is true.
In dicot stem amount of secondary xylem is MORE THAN that secondary phloem.

Question 3

A: In dicot stem, outer hypodermis consists of a few layers of collenchymatous cells just below the epidermis.
R: Hypodermis layer in dicot stem provides mechanical strength to the the young stem.

Answer 3

D) Both A and R are true and R is the correct explanation of A.

Question 3

A: Guard cells are dumb bell shaped in grasses.
R: Guard cells possess chloroplast and regulate the opening and closing of stomata

Answer 3

A) Both A and R are true but R is not the correct explanation of A.
Shape of guard cells doesn’t explain its functions.

Question 4

A: The nucleus of companion cells controls the functions of sieve tubes.
R: A mature sieve element possesses a peripheral cytoplasm and a large vacuole.

Answer 4

A) Both A and R are true but R is not the correct explanation of A.
The nucleus of companion cell controls the function of mature sieve tube because mature sieve tubes lack nucleus.

Question 5

A: Monocot roots do not undergo any secondary growth
R: Closed vascular bundles are present in monocot roots.

Answer 5

D) Both A and R are true and R is the correct explanation of A.

Question 6

A: The cells of collenchyma tissue are significantly thickened at the corners.
R: Collenchyma provides structural support to the growing parts of the plant.

Answer 6

D) Both A and R are true and R is the correct explanation of A.

Question 7

A: Intercalary meristem occurs between mature tissues especially in grasses.
R: Intercalary meristem regenerates parts removed by grazing herbivores in grasses.

Answer 7

D) Both A and R are true and R is the correct explanation of A.

Question 8

1: Cork cambium, interfascicular cambium and fascicular vascular cambium are examples of lateral meristem which produces secondary tissues.
2: Vascular tissues, ground tissues and dermal tissues are produced by the specific regions of the apical meristem during the formation of the secondary plant body.

Answer 8

1 is correct 2 is incorrect.
vascular, ground and dermal tissues are formed during the formation of the primary plant body.

Question 9

1: In monocot plants, collenchyma occurs in layers below the epidermis and found either in patches or as a homogeneous layer.
2: sclerenchyma consists of long narrow cells with thick, lignified cell walls having a few or numerous pits.

Answer 9

1 is incorrect, 2 is correct.
In dicot plants, collenchyma occurs in patches or a homogeneous layer.

Question 10

1: Parenchyma forms the major component within organs and perform various functions like photosynthesis, storage, secretion,etc.
2: Gymnosperms lack vessels in their xylems, whereas in flowering plants, xylem parenchyma and vessels are the main water transporting elements.

Answer 10

D) Both 1 and 2 are correct.

Question 11

1: Food is stores in the form of starch or fat in xylem parenchyma.
2: Exarch is the arrangement of primary xylem and metaxylem in stem where the protoxylem lies towards the pith and metaxylem lies towards the periphery of the organ.

Answer 11

1 is correct , 2 is incorrect.
Endarch is the arrangement of primary xylem and metaxylem in stem where the protoxylem lies towards the pith and metaxylem lies towards the periphery of the organ.

Question 12

1: Phloem fibres are much elongated and unbranched. These are present in primary phloem, but generally absent in secondary phloem.
2: Protophloem is the first formed primary phloem and consists of the bigger sieve tubes, while metaphloem is the later formed phloem having narrow sieve tubes.

Answer 12

Both 1 and 2 are incorrect.
Phloem fibres are present in secondary phloem but are absent in primary phloem.
Protophloem has narrow sieve tubes and metaphloem has bigger sieve tubes.

Question 13

1: At some places, secondary medullary rays are formed by the cambium, which passes through the secondary xylem and the secondary in axial directions.
2: Sapwood is lighter in colour and present at the peripheral region of the secondary phloem.

Answer 13

Both 1 and 2 are incorrect.
Secondary medullary rays are formed in radial directions.
Sapwood is present in secondary xylem.

Question 14

1: at certain regions, closely arranged parenchymatous cells are cut off by phellogen on the inner side instead of cork cells.
2: The outer cells of phellogen differentiate into phelloderm, while the inner cells differentiate into phellem.

Answer 14

Both 1 and 2 are incorrect.
phellogen cuts off parenchymatous cells on the OUTER SIDE.
Outer cells of phellogen: PHELLEM
Inner cells of phellogen: PHELLODERM OR SECONDARY CORTEX

Question 15

Which of the following statements are correct?
1. Highly thickened walls and obliterated central lumens are found in xylem fibres which may either be septate or aseptate.
2. Metaxylem is the later formed primary xylem, while protoxylem is the first formed primary xylem.
3. Nucleus, large vacuole and peripheral cytoplasm are present in a mature sieve tube element.
4. Ground tissue in leaves is termed as mesophyll, which comprises of chloroplast containing cells with thick walls.

Answer 15

1 and 2 are correct.
Nucleus in ABSENT in SIEVE TUBE ELEMENT.
Mesophyll cells have THIN WALLS.

Question 16

Which of the following statements are correct?
1. Heartwood is the central, dark coloured, non functional part of the secondary xylem of an old stem, which do not conduct water.
2. Centrally located vascular bundles are usually smaller than the peripheral vascular bundles in monocot stem.
3. The ground tissue of plants include all the tissues that are neither dermal or vascular and consists of simple tissues.
4. Xylem is a complex tissue which provide mechanical strength to the plants parts, and is comprised of 5 different kinds of elements.

Answer 16

1 and 3 are correct.
monocot stem:
conjoint
closed
central vascular bundles are LARGER THAN peripheral vascular bundles.
xylem has only 4 kinds of elements:
xylem parenchyma
xylem fibres
tracheids
vessels

Question 17

Identify the incorrect statements:
1. In most of the dicot stem and root, secondary growth increases the girth of the organ by the activity of cork cambium and the vascular cambium.
2. Main bulk of the plant is formed by the ground tissue which is divided into 3 zones.
3. Vascular cambium is completely secondary in origin, and originates from the tissue located just above the phloem bundle.
4. The amount of secondary xylem produced is more than secondary phloem because generally cambium is more active towards outer side than on the inner side.

Answer 17

2 and 4 are incorrect.
secondary xylem is more active on the inner side than the outer side

Question 18

Which of the following statements are correct?
1. Ray parenchymatous cells conduct water radially.
2. Companion cells and sieve tubes are interconnected by pit fields present between their common transverse walls.
3. Trichomes are the epidermal hairs on the stem, which help in preventing water loss due to transpiration.
4. The monocot stem has a large, conspicuous ground tissue and parenchymatous hypodermis.

Answer 18

1 and 3 are correct.
Companion cells and sieve tubes are interconnected by pit fields present between their common LONGITUDINAL walls.
Monocot stem has a SCLERENCHYMATOUS HYPODERMIS.

Question 19

Identify the correct statements:
1. Phellem is made up of narrow, thin walled and nearly rectangular cells, which cut off cells on both the sides.
2. Dicots exhibit both primary and secondary growth and cork and vascular cambium are involved in the secondary growth.
3. Isobilateral leaf shows similar anatomy to that of the dorsiventral leaf in many ways.
4. Pith is small or inconspicuous in monocot root, while in dicots pith is large and well developed.
5. Opening and closing of stomata is regulated by bean shaped guard cells containing chloroplasts.

Answer 19

2,3 and 4 are correct.
PHELLOGEN is made up of narrow, thin walled and nearly rectangular cells on both the sides.
Pith:
Monocot: large and well developed
Dicot: small or inconspicuous

Question 20

Identify the incorrect statements:
1. Technical term that refers to all the tissues exterior to the vascular cambium is bark.
2. Deposition of organic compounds and essential oils in the innermost layers of the stem, makes greater part of the secondary xylem dark.
3. Cambial ring becomes active and starts to cut off new cells, and the cells that cut off towards the pith mature into secondary phloem.
4. Reticulate venation is found in dicots leaves and their veins vary in thickness.
5. Anatomy of the monocot root shows epidermis, endodermis, cortex, pericycle and pith.

Answer 20

1 and 3 are correct.
Bark is a NON TECHNICAL TERM.
Cells cut off towards the pith: SECONDARY XYLEM

Question 21

Identify the correct statements:
1. Starch sheath is layers of cells of the endodermis which are rich in starch grain.
2. stomata are present in equal number on both the surfaces of the epidermis of the dorsiventral leaf.
3. The cells of the medullary rays, adjoining these interfascicular cambium becomes meristematic and forms the intrafascicular cambium.
4. The age of the tree is estimated on the basis of the annual rings seen in a cut stem.
5. Lenticels occur in most woody trees, which allow the exchange of gases between the outer atmosphere and the internal tissue of the stem.

Answer 21

1, 4 and 5 are correct.
In dorsiventral leaf, no of stomatas:
upper(adaxial epidermis) < lower(abaxial epidermis)

medullary rays -> intrafascicular cambium -> interfascicular cambium.

Question 22

Identify the correct statements:
1. Due to the activity of the cork cambium, pressure builds up on the remaining layers peripheral to phellogen and ultimately these layers die and slough off.
2. Early or soft bark do not have secondary phloem.
3. Unlike dicot roots, the vascular cambium is completely secondary in origin in dicot stems.
4. In the spring season, cambium is very active.
5. Vascular cambium activity is under the control of many physiological and environmental factors.

Answer 22

1, 4 and 5 are correct.
soft bark HAS SECONDARY PHLOEM.
DICOT STEM: Vascular cambium : SECONDARY IN ORIGIN
DICOT ROOT: partially secondary + partially primary